Game System, Game System Control Method and Information Storage Medium

ABSTRACT

To provide a game system that enables a degree of difficulty of an occurrence of a predetermined game event to be changed depending on a degree of proficiency of a player in a game in which the predetermined event is made to occur when a controller is operated according to specific procedures. The present invention relates to a game system including one or more controllers. In the game system, a determining unit ( 52 ) determines whether or not a criterion operation data string has been inputted from the controller, a game event generation unit ( 58 ) generates a predetermined game event according to a result of the determination made by the determining unit ( 52 ), and the determining unit ( 52 ) changes the criterion operation data string based on a result of a past determination on at least one of the one or more controllers.

TECHNICAL FIELD

The present invention relates to a game system, a game system controlmethod, and an information storage medium.

BACKGROUND ART

Such a game is known that when a controller is operated according tospecific procedures, a game event capable of exerting a larger change ina state of a game is caused. For instance, as a fighting game in which agame character operated by a player engages in battle with a gamecharacter operated by a computer or an opponent player, there is known afighting game in which a special skill event is caused, which involvesthe game character performing a special skill capable of exerting agreater damage on the opponent game character, when the controller isoperated according to specific procedures.

[Patent Document 1] JP 3153761 B

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In the game as described above, if a degree of proficiency of the playerimproves and the game event described above is easily caused, afascination aspect of the game may be spoiled. For example, in thefighting game as described above, if the special skill event is easilycaused, it becomes possible to give greater damage to the opponent gamecharacter easily, resulting in the spoiling of the fascination aspect ofthe fighting game.

The present invention has been made in view of the problems given above,and it is an object of the present invention to provide a game system, agame system control method, and an information storage medium that arecapable of changing a degree of difficulty of an occurrence of apredetermined game event on the basis of a degree of proficiency of aplayer in a game in which the predetermined game event occurs when acontroller is operated according to specific procedures.

Means for Solving the Problems

To solve the above-mentioned problems, according to one aspect of thepresent invention, there is provided a game system including one or morecontrollers, including: determining means for determining whether or nota criterion operation data string has been inputted from the one or morecontrollers; and game event generation means for generating apredetermined game event according to a result of the determination madeby the determining means, in which the determining means executes achange of the criterion operation data string on the basis of a resultof a past determination on at least one of the one or more controllers.

According to another aspect of the present invention, there is provideda control method for a game system including one or more controllers,including: a determining step of determining whether or not a criterionoperation data string has been inputted from the one or morecontrollers; and a game event generation step of generating apredetermined game event according to a result of the determination madein the determining step, in which the determining step includes the stepof executing a change of the criterion operation data string on thebasis of a result of a past determination on at least one of the one ormore controllers.

According to still another aspect of the present invention, there isprovided a program for causing a computer such as a home game machine, acommercial game machine, a portable game machine, a mobile phone, apersonal computer, or a server computer to function as a game systemincluding one or more controllers, and also to function as: determiningmeans for determining whether or not a criterion operation data stringis inputted from the one or more controllers; and game event generationmeans for generating a predetermined game event according to a result ofthe determination made by the determining means, in which thedetermining means executes a change of the criterion operation datastring on the basis of the result of the past determination on at leastone of the one or more controllers.

According to still another aspect of the present invention, there isprovided a computer readable information storage medium storing theprogram described above. Yet further, a program distribution deviceaccording to the present invention is a program distribution deviceincluding an information storage medium storing the program, for readingthe program from the information storage medium and distributing theprogram. Furthermore, a program distribution method according to thepresent invention is a program distribution method, while using aninformation storage medium storing the program, for reading the programfrom the information storage medium and distributing the read program.

The present invention relates to a game system including one or morecontrollers. In the present invention, it is determined whether or notthe criterion operation data string is inputted from the one or morecontroller, and the predetermined game event occurs according to theresult of the determination. Particularly, in the present invention, thecriterion operation data string is changed based on the result of thepast determination on at least one of the one or more controllers.According to the present invention, the degree of difficulty of theoccurrence of the predetermined game event can be changed based on thedegree of proficiency of the player.

In one example of the present invention, the determining means mayexecute, when determining whether or not the criterion operation datastring has been inputted from one of the one or more controllers, thechange on the basis of a result of a past determination on thecontroller.

In another example of the present invention, the determining means mayexecute, when determining whether or not the criterion operation datastring has been inputted from one of the one or more controllers, thechange on the basis of a result of a past determination on anothercontroller among the one or more controllers.

In still another example of the present invention, the determining meansmay execute the change on the basis of the number of times the gameevent generation means has generated the predetermined game eventaccording to the result of the determination on at least one of the oneor more controllers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a hardware structure of a game deviceaccording to an embodiment of the present invention.

FIG. 2 are diagrams showing an example of a controller.

FIG. 3 is a functional block diagram of the game device according to theembodiment of the present invention.

FIG. 4 is a diagram showing an example of a criterion operation datastring table.

FIG. 5 is a diagram showing an example of a determination result table.

FIG. 6 is a diagram showing an example of an occurrence count conditiontable.

FIG. 7 is a diagram showing an example of an occurrence count table.

FIG. 8 is a flowchart showing a game process.

FIG. 9 is a flowchart showing an input determining process.

FIG. 10 is a flowchart showing the input determining process.

FIG. 11 is a diagram showing another example of the criterion operationdata string table.

FIG. 12 is a diagram showing an example of the occurrence countcondition table.

FIG. 13 is a flowchart showing another example of the input determiningprocess.

FIG. 14 is a diagram showing a whole structure of a program distributionsystem according to another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

An in-depth description of an example of an embodiment of the presentinvention will hereinafter be given based on the drawings.

FIG. 1 is a diagram illustrating a hardware structure of a game device(game system) according to the embodiment of the present invention. Agame device 10 illustrated in FIG. 1 has a structure in which a DVD-ROM25 and memory cards 28 as information storage mediums are inserted intoa home game machine 11, and a monitor 18 and a speaker 22 are connectedto the home game machine 11. For example, a domestic TV receiving set isused for the monitor 18, and a built-in speaker thereof is used for thespeaker 22.

The home game machine 11 is a well-known computer game system comprisinga bus 12, a microprocessor 14, an image processing unit 16, a soundprocessing unit 20, a DVD-ROM reproducing unit 24, a main memory 26, aninput/output (I/O) processing unit 30, and controllers 32. An enclosureaccommodates the components other than the controllers 32.

The bus 12 is used for exchanging addresses and/or data among therespective units of the home game machine 11. The microprocessor 14, theimage processing unit 16, the main memory 26, and the I/O processingunit 30 are connected to each other via the bus 12 so as to becommunicable with each other.

The microprocessor 14 controls the individual units of the home gamemachine 11 on the basis of an operating system stored in a ROM (notshown), a program read from the DVD-ROM 25, and data read from thememory card 28. The main memory 26 comprises, for example, a RAM, andthe program read from the DVD-ROM 25 and the data read from the memorycard 28 are written in the main memory 26 if necessary. The main memory26 is also employed as a work memory for the microprocessor 14.

The image processing unit 16, comprising a VRAM, renders a game screeninto the VRAM based on the image data sent from the microprocessor 14.Then, the image processing unit 16 converts a content thereof into videosignals and outputs the video signals to the monitor 18 at predeterminedtimes.

The I/O processing unit 30 is an interface used for the microprocessor14 to access the sound processing unit 20, the DVD-ROM reproducing unit24, the memory card 28, and the controller 32. The sound processing unit20, the DVD-ROM reproducing unit 24, the memory card 28, and thecontroller 32 are connected to the I/O processing unit 30.

The sound processing unit 20, comprising a sound buffer, reproduces andoutputs, via the speaker 22, various sound data such as game music, gamesound effects, messages or the like, read from the DVD-ROM 25 and storedin the sound buffer.

The DVD-ROM reproducing unit 24 reads the program stored on the DVD-ROM25 in accordance with an instruction given from the microprocessor 14.It is to be noted that the DVD-ROM 25 is employed for supplying theprogram to the home game machine 11. However, any of various otherinformation storage medium such as CD-ROMs, ROM cards or the like mayalso be used. Further, the program may also be supplied to the home gamemachine 11 from a far-off area via a data communication network such asthe Internet or the like.

The memory card 28 comprises a nonvolatile memory (e.g., an EEPROM). Thehome game machine 11 has a plurality of memory card slots for insertionof the memory cards 28, whereby the plurality of memory cards 28 can besimultaneously inserted. The memory card 28 is constructed so that thememory card 28 can be inserted into and removed from the memory cardslot, and is employed for storing various game data such as save data orthe like.

The controller 32 is a general-purpose operation input means used for aplayer to input a variety of game operations. When the controller 32 isoperated, operation data indicating a content of the operation issupplied to the microprocessor 14. More specifically, statuses of therespective units of the controller 32 are scanned at an interval of afixed period (e.g., every 1/60 sec) by the I/O processing unit 30. Then,operation data (operation signal) representing a result of the scan istransferred via the bus 12 to the microprocessor 14. The microprocessor14 determines, based on the operation data, the game operation of theplayer. The home game machine 11 is configured to be connectable withthe plurality of controllers 32, and configured so that the game iscontrolled based on the operation data inputted from the respectivecontrollers 32.

FIG. 2 are diagrams showing an example of the controller 32. Thecontroller 32 shown in FIG. 2 is a general-purpose game controller. Asillustrated in FIG. 2( a), the surface of the controller 32 is providedwith a direction button 34, a start button 36, and buttons 38X, 38Y,38A, and 38B. The surfaces of the buttons 38X, 38Y, 38A, and 38B aremarked with symbols of “square”, “triangle”, “cross”, and “circle”,respectively. Further, as illustrated in FIG. 2( b), the buttons 42L,42R, are formed on the top surface on the left and right sides thereofcloser to the front surface, and the buttons 40L, 40R, are similarlyformed but closer to the rear surface. The direction button 34 takes across-shape and is normally used for designating a moving direction of acharacter or a cursor. The start button 36 is a small-sized push buttonhaving a triangular shape and is normally used for starting or forciblyterminating the game. The buttons 38X, 38Y, 38A, 38B, 40L, 40R, 42L, and42R are used for other game operations.

In the game device 10 having the hardware structure as described above,a game program read from the DVD-ROM 25 is executed by themicroprocessor 14 to provide a fighting game.

The fighting game includes a 1-player mode and a 2-player mode. The1-player mode is a game mode for engaging in battle a game characteroperated by the player (which will hereinafter be referred to asoperation object character) and a game character operated by thecomputer. Further, the 2-player mode is a game mode for engaging inbattle the operation object character and a game character operated byan opponent player. The following discussion proceeds in a way thatexemplifies the 2-player mode.

A first operation object character and a second operation objectcharacter are displayed on the game screen for the 2-player mode. Thefirst operation object character is defined as an operation object ofthe first player. The first operation object character performs avariety of skills based on contents of operations of a first controller(controller 32 used by the first player). The second operation objectcharacter is defined as an operation object of the second player. Thesecond operation object character performs the variety of skills basedon contents of operations of a second controller (controller 32 used bythe second player).

Those operation object characters perform, when the direction button 34and the buttons 38B, 38X, and 38Y of each controller 32 are operated inspecified procedures, special skills capable of exerting greater damageon the opponent than by normal skills (such as punching and kicking). Inother words, in the game device 10, when a specific criterion operationdata string is inputted by each controller 32, such a special skillevent occurs to cause the operation object character to perform thespecial skill.

In particular, in the fighting game according to this embodiment, it ispossible to differentiate a degree of difficulty of the occurrence ofthe special skill event for every player on the basis of a degree ofproficiency of individual players. To be specific, the number ofoccurrences of the special skill events is counted on a player-by-playerbasis, and, with regard to a player with an event occurrence countreaching a predetermined count, the operation procedures (criterionoperation data string) for causing the occurrence of the special skillevent are changed to more complicated procedures. In other words, aplayer with more occurrences of the special skill events is determinedto be a player having a high degree of proficiency, and the degree ofdifficulty of the occurrence of the special skill event is thusincreased. As a result, for example, even when players who are differentin terms of degrees of proficiency engage in battle, the battle can beenlivened.

Given herein is a description of a functional configuration of the gamedevice 10. FIG. 3 mainly shows functional blocks related to the presentinvention among the functional blocks realized in the game device 10. Asshown in FIG. 3, the game device 10 includes an operation unit 50, adetermining unit 52, a statistic acquisition unit 56, and a game eventgeneration unit 58. Those functions are realized by the microprocessor14 executing the program supplied via the DVD-ROM 25.

[1. Operation Unit]

The operation unit 50 is realized mainly with the controller 32 and theI/O processing unit 30. The operation data inputted from the operationunit 50 is held in a key buffer.

[2. Determining Unit]

The determining unit 52 determines whether or not the operation datastring corresponding to the criterion operation data string is inputtedfrom the operation unit 50 within a determination target period. Notethat the determination target period is defined as, e.g., a period froma predetermined time ago up to the present time.

The determining unit 52 stores a criterion operation data string tableas illustrated in FIG. 4, for example. The criterion operation datastring table illustrated in FIG. 4 contains an ID field, a criterionoperation data string field, and a skill event field. The ID fieldstores identification information for uniquely identifying the criterionoperation data string. The criterion operation data string field storesinformation specifying the criterion operation data string. Thecriterion operation data string includes a single item or a plurality ofitems of operation data, and indicates the operation procedures for thecontroller 32. In the example of FIG. 4, the criterion operation datastring having ID“1” is an operation data string obtained by combiningthe operation data corresponding to a downward instructing portion ofthe direction button 34, the operation data corresponding to a rightwardinstructing portion of the direction button 34, and the operation datacorresponding to the button 38Y, in the stated order. The skill eventfield stores information indicating the skill event that occurs when thecriterion operation data string is inputted from the operation unit 50.As shown in FIG. 4, according to this embodiment, the special skillevent includes a special skill A event and a special skill B event. Inother words, two types of skills such as the special skill A and thespecial skill B are prepared as the special skills that can be performedby the operation object character.

Further, the determining unit 52 stores a determination result table asillustrated in FIG. 5, for example. The determination result table shownin FIG. 5 contains an ID field and a determination result flag field.The ID field stores an ID of the criterion operation data string. Thedetermination result flag field stores information indicating a resultof the determination made by the determining unit 52. To be specific,when determining that the criterion operation data string is inputted,“1” is stored therein. Further, when determining that the criterionoperation data string is not inputted, “0” is stored therein. It is tobe noted that the determination result table may also be provided forevery player (each controller 32).

[3. Determination Criterion Changing Unit]

The determining unit 52 includes a determination criterion changing unit54. The determination criterion changing unit 54 changes, based on theresults of the determinations made in the past by the determining unit52, the criterion operation data string to be inputted for causing theoccurrence of the special skill event (predetermined game event). Morespecifically, the determination criterion changing unit 54 implementssuch a change based on a statistic acquired by the statistic acquisitionunit 56 that will be explained later on.

The determination criterion changing unit 54 stores an occurrence countcondition table as illustrated in FIG. 6, for example. The occurrencecount condition table shown in FIG. 6 contains an ID field and anoccurrence count condition field. The ID field stores an ID of thecriterion operation data string. The occurrence count condition fieldstores information indicating a condition on the number of theoccurrences of the special skill event (occurrence count condition).

When it is determined that the criterion operation data stringcorresponding to the special skill event is inputted, if the occurrencecount condition associated with the criterion operation data string issatisfied, the determination criterion changing unit 54 permits thespecial skill event to occur. On the other hand, when it is determinedthat the criterion operation data string corresponding to the specialskill event is inputted, if the occurrence count condition associatedwith the criterion operation data string is not satisfied, thedetermination criterion changing unit 54 restricts the occurrence of thespecial skill event.

Note that the criterion operation data string specified by ID“1” and thecriterion operation data string specified by ID“2” that contains moreitems of operation data, are associated with the special skill A eventin this embodiment (see FIG. 4). Further, an occurrence count condition“equal to or larger than 0 but less than 5” is associated with thecriterion operation data string specified by ID“1”, and an occurrencecount condition “equal to or larger than 5” is associated with thecriterion operation data string specified by ID“2” (see FIG. 6).Therefore, a more complicated operation is required for causing theoccurrence of the special skill A event for a player who has caused thespecial skill A event to occur five or more times. Similarly, thecriterion operation data string specified by ID“3” and the criterionoperation data string specified by ID“4” that contains more items ofoperation data, are associated with the special skill B event (see FIG.4). Further, the occurrence count condition “equal to or larger than 0but less than 5” is associated with the criterion operation data stringspecified by ID“3”, and the occurrence count condition “equal to orlarger than 5” is associated with the criterion operation data stringspecified by ID“4” (see FIG. 6). Hence, a more complicated operation isrequired for causing the occurrence of the special skill B event for aplayer who has caused the special skill B event to occur five or moretimes.

[4. Statistic Acquisition Unit]

The determining unit 52 includes the statistic acquisition unit 56. Thestatistic acquisition unit 56 acquires a statistic related to theresults of the past determinations (past determination statuses) by thedetermining unit 52. The “statistic related to the results of the pastdeterminations by the determining unit 52” is, for example, theoccurrence count of the special skill event. Furthermore, for instance,the statistic may also be a determination count by which the determiningunit 52 has determined that each criterion operation data string hasbeen inputted.

In this embodiment, the statistic acquisition unit 56 retains anoccurrence count table as illustrated in FIG. 7, for example. Theoccurrence count table shown in FIG. 7 contains a PID field, a specialskill event field, and an occurrence count field. The PID field storesidentification information for uniquely identifying the player (or thecontroller 32). The special skill event field stores informationindicating a type of the special skill event. The occurrence count fieldstores information indicating the number of occurrences of the specialskill event caused by the player (or an input from the controller 32thereof). The occurrence count table retains the occurrence count ofeach special skill event for every player (every controller 32).

Note that results of the acquisitions by the statistic acquisition unit56, i.e. contents of the occurrence count table, may be initialized eachtime the game is finished (each time a fight ends in the case of thebattle game), for example. Moreover, for instance, the contents of theoccurrence count table may be initialized when a predetermined period oftime elapses since the last play time, or may be initialized when playsare held a predetermined number of times (matches or battles areconducted a predetermined number of times). Further, for example, thecontents of the occurrence count table may be stored in the memory card28 to be reflected in the games from the next game onward. In the lattercase, the criterion operation data string may be prevented from beingchanged in the middle of the game and instead changed at the start ofthe game, based on the result of the acquisition in the last game or onthe results of the acquisitions in the games up to the last time.

[5. Game Event Generation Unit]

The game event generation unit 58 generates the skill event according tothe result of the determination made by the determining unit 52.Specifically, when it is determined that the criterion operation datastring is inputted, the game event generation unit 58 causes the skillevent corresponding to the criterion operation data string to occur. Theskill event is defined as a game event which makes the operation objectcharacter perform the skill corresponding to the criterion operationdata string. When the skill event occurs, motion data (animation data)of the skill starts to be reproduced, and a scene of how the operationobject character performs the skill is displayed on the game screen.

Explained herein is a game process executed by the game device 10 at aninterval of a predetermined period of time (e.g., every 1/60 sec). FIG.8 is a flowchart showing the game process.

As illustrated in FIG. 8, in the game process, first, an inputdetermining process is executed with respect to an input from the firstcontroller (S101). FIGS. 9 and 10 are flowcharts each showing the inputdetermining process.

As illustrated in FIG. 9, in the input determining process, first, avariable n is initialized to “1” (S201).

After that, the determining unit 52 determines whether or not it is atime at which the skill event associated with ID“n” can be caused(S202). In this embodiment, when a certain skill event occurs, i.e.,when the reproduction of the motion data (animation data) of the certainskill is started, the occurrence of the skill event having apredetermined relationship with the certain skill event is restricted.Thus, the determining unit 52 determines whether or not the skill eventassociated with ID“n” is allowed.

The determining unit 52, when determining that it is not the time atwhich the skill event associated with ID“n” can be caused, updates thedetermination result flag field associated with ID“n” to 0 (S205).

On the other hand, the determining unit 52, when determining that it isthe time at which the skill event associated with ID“n” can be caused,determines whether or not the operation data string corresponding to thecriterion operation data string specified by ID“n” is inputted withinthe determination target period (S203). To be specific, the determiningunit 52 acquires the criterion operation data string specified by ID“n”from the criterion operation data string table. Then, the determiningunit 52 refers to the content of the key buffer corresponding to thecontroller 32 set as an object of the input determining process (whichwill hereinafter be referred to as object controller) to determinewhether the criterion operation data string is contained in theoperation data string inputted during a period from a predetermined timeago up to the present time. If the input times of two consecutive itemsof operation data are apart from each other by a predetermined period (acriterion interval) or more, however, the determining unit 52 does notdetermine that the acquired criterion operation data string is containedtherein.

The determining unit 52 updates, when it is determined that thecriterion operation data string specified by ID“n” is inputted, thedetermination result flag field associated with ID“n” to “1” (S204). Onthe other hand, when determining that the criterion operation datastring specified by ID“n” is not inputted, the determining unit 52updates the determination result flag field associated with ID“n” to 0(S205).

After that, the determining unit 52 increments the variable n (S206),and determines whether or not the criterion operation data stringspecified by ID“n” exists (S207). When it is determined that thecriterion operation data string specified by ID“n” exists, the processesof S202 through S207 are executed. Thus, in this embodiment, it isdetermined whether or not the criterion operation data string isinputted from the operation unit 50, and the result of thisdetermination is stored in the determination result table.

On the other hand, if it is determined that the criterion operation datastring specified by ID“n” does not exist, i.e., when the processesdescribed above are executed with respect to all of the criterionoperation data strings, a variable m is initialized to “1” (S208). Afterthat, the determining unit 52 determines whether or not the value of thedetermination result flag field associated with ID“m” is “1” (S209).

When the value of the determination result flag field is determined tobe “1”, the determination criterion changing unit 54 determines whetheror not the occurrence count condition is associated with the criterionoperation data string specified by ID“m” (S210). This determination ismade based on the occurrence count condition table. It is to be notedthat the occurrence count condition is associated with only the specialskill event in this embodiment, and hence it may be determined whetheror not the skill event associated with ID“m” is the special skill event(special skill A event or special skill B event).

When it is determined that the occurrence count condition is notassociated therewith, the game event generation unit 58 updateson-occurrence event information (S213). The on-occurrence eventinformation is information indicating a type of the skill event that isbeing caused, and is stored in the main memory 26. The game eventgeneration unit 58 updates the on-occurrence event information so as tospecify the skill event associated with ID“m”.

On the other hand, when determining that the occurrence count conditionis associated therewith, the determination criterion changing unit 54determines whether the occurrence count condition is satisfied or not(S211). Specifically, the determination criterion changing unit 54refers to the occurrence count table and the occurrence count conditiontable, thereby determining whether or not the occurrence countassociated with a combination of the player corresponding to the objectcontroller and the type of the special skill event associated with ID“m”satisfies the occurrence count condition associated with ID“m”.

In the case where it is determined that the occurrence count conditionis satisfied, in the occurrence count table, the statistic acquisitionunit 56 increments the value of the occurrence count field associatedwith the combination of the player corresponding to the objectcontroller and the special skill event associated with ID“m” (S212).After that, the game event generation unit 58 updates the on-occurrenceevent information so as to specify the special skill event associatedwith ID“m” (S213).

After executing the process of S213, the content of the key buffercorresponding to the object controller is cleared (S214), thuscompleting the input determining process.

In contrast, when it is determined in S209 that the value of thedetermination result flag field is not “1”, or when it is determined inS211 that the occurrence count condition is not satisfied, the variablem is incremented (S215). Then, it is determined whether or not thecriterion operation data string specified by ID“m” exists (S216). If thecriterion operation data string specified by ID“m” exists, the processof S209 is executed. On the other hand, if the criterion operation datastring specified by ID“m” does not exist, the input determining processis terminated.

Note that the processes of S210 and S211 may be executed beforeexecuting the process of S203 in the case where it is determined in S202that it is the time at which the skill event associated with ID“n” canbe caused. In this case, if it is determined that the occurrence countcondition is not associated with ID“n”, the process of S203 may beexecuted. Further, when it is determined that the occurrence countcondition is not satisfied, the process of S205 may be executed.

When the input determining process with respect to the input from thefirst controller is completed, next, the input determining process withrespect to the input from the second controller is executed (S102). Theinput determining process with respect to the input from the secondcontroller is executed in the same way as the input determining processwith respect to the input from the first controller. Note that theprocess of this step is omitted in the case of the 1-player mode.

When the input determining processes with respect to the inputs from thefirst controller and the second controller are completed, the game eventgeneration unit 58 creates the game screen in the VRAM (S103). Forexample, the game event generation unit 58 creates, based on theon-occurrence event information retained in the main memory 26, the gamescreen on which how the first operation object character and the secondoperation object character perform the skills is displayed. The gamescreen created in the VRAM is output to the monitor 18 at thepredetermined time.

Note that the game processes described above are realized by themicroprocessor 14 executing the game program read from the DVD-ROM 25.

As discussed above, according to the game device 10, the operationprocedures for causing the occurrence of the special skill event(special skill A event and special skill B event) can be changed basedon the degree of proficiency of the player. In other words, the degreeof difficulty of the occurrence of the special skill event can bechanged based on the degree of proficiency of the player. As a result,it becomes possible to prevent a fascination aspect of the game frombeing spoiled due to the fact that the special skill event is caused tooccur easily. For instance, even when the players are different in theirdegrees of proficiency, a fervent battle can be held therebetween.

Note that in the above description, the degree of difficulty of theoccurrence of the special skill event is varied by changing thecriterion operation data string for causing the occurrence of thespecial skill event. However, the degree of difficulty of the occurrenceof the special skill event may also be varied by changing a length ofthe determination target period. To be specific, with respect to theplayer who has caused the special skill A event five or more times, thetime for conducting the operation procedures for causing the occurrenceof the special skill A event may be reduced by shortening thedetermination target period. Similarly, regarding the player who hascaused the special skill B event five or more times, the time forconducting the operation procedures for causing the occurrence of thespecial skill B event may be reduced by shortening the determinationtarget period.

In this case, in the criterion operation data string table, asillustrated in FIG. 11, a single criterion operation data string may beassociated with one special skill event.

Further, as illustrated in FIG. 12, the occurrence count condition tablemay be structured so that the occurrence count condition is associatedwith the length of the determination target period. Note that T1 and T2are predetermined constants each representing the length of time in FIG.12, where T2 is a time shorter than T1.

Moreover, in the input determining process, instead of the processes ofS201 through S207, processes shown in FIG. 13 may be executed.

In the processes illustrated in FIG. 13, to begin with, the variable nis initialized to “1” (S301). After that, it is determined whether ornot it is the time at which the skill event associated with ID“n” can becaused (S302). Those processes are executed in the same way as S201 andS202 of FIG. 9.

When it is determined that it is the timing at which the skill eventassociated with ID“n” can be caused, the determination criterionchanging unit 54 determines whether or not the skill event associatedwith ID“n” is the special skill event (special skill A event or specialskill B event) (S303).

The determination criterion changing unit 54 determines, when it isdetermined that the skill event is not the special skill event, thelength of the determination target period as the predetermined timelength (e.g., T1) (S306). On the other hand, when it is determined thatthe skill event is the special skill event, the determination criterionchanging unit 54 refers to the occurrence count table, thereby acquiringthe occurrence count associated with the combination of the playercorresponding to the object controller and the special skill eventassociated with ID“n” (S304). Then, the determination criterion changingunit 54 refers to the occurrence count condition table and thusdetermines, as the length of the determination target period, the timelength associated with the occurrence count condition satisfied by theacquired occurrence count (S305).

After that, the determining unit 52 determines whether or not thecriterion operation data string specified by ID“n” is inputted withinthe determination target period (S307). Then, the determining unit 52updates the determination result flag field associated with ID“n” to “0”or “1”, according to the result of the determination (S308 and S309).After that, the determining unit 52 increments the variable n (S310),and determines whether or not the criterion operation data stringspecified by ID“n” exists (S311). If it is determined that the criterionoperation data string specified by ID“n” exists, the process of S302 isexecuted again. Moreover, if it is determined that the criterionoperation data string specified by ID“n” does not exist, the processesof S208 through S216 shown in FIG. 10 are executed. Note that theprocesses of S307 through S311 are executed in the same way as theprocesses of S203 through S207 in FIG. 9.

With the structure as described above, the length of the determinationtarget period can be changed based on the degree of proficiency of theplayer. In other words, even with the structure as described above, thedegree of difficulty of the occurrence of the special skill event can bechanged based on the degree of proficiency of the player.

Here, in this embodiment, in determining whether or not the criterionoperation data string is inputted, if the input times of two consecutiveitems of operation data are apart from each other by the interval of thepredetermined period (criterion interval) or longer, it is notdetermined that the criterion operation data string is contained (referto S307 and S203). Thus, the length of the determination target periodmay be varied by changing the length of this criterion interval ratherthan the length of the whole determination target period. The degree ofdifficulty of the occurrence of the special skill event may also bechanged as described above. For example, the degree of difficulty of theoccurrence of the special skill event may be raised by shortening thecriterion interval. The degree of difficulty of the occurrence of thespecial skill event may be lowered by elongating the criterion interval.

Note that the present invention is not limited to the embodimentdiscussed above.

For instance, the degree of difficulty of the occurrence of the specialskill event may be lowered based on the degree of proficiency of theplayer. For example, in the 1-player mode, the degree of difficulty ofthe occurrence of the special skill event is decreased based on thedegree of proficiency of the player, whereby the player can more easilycause the special skill event to occur. With this structure, an increasein level of the player or of the operation object character may bestaged. Further, for example, in the 2-player mode, if the occurrencecount of the special skill event of one player reaches a predeterminedcount, the operation procedures (criterion operation data string) forcausing the occurrence of the special skill event may be changed toeasier procedures for the other player, or the determination targetperiod may be elongated for the other player. Thus, based on the degreeof proficiency of the one player, the degree of difficulty of theoccurrence of the special skill event for the other player may bedecreased. Accordingly, even when the players are different in theirdegrees of proficiency, a fervent battle can be held therebetween.

Further, for instance, in the 2-player mode, the degree of difficulty ofthe occurrence of the special skill event for at least one player may bechanged based on a difference between the occurrence count of thespecial skill event of one player and the occurrence count of thespecial skill event of the other player. Even with such change, afervent battle can be held between players who have different degrees ofproficiency.

Moreover, for example, the statistic acquisition unit 56 may store adate and time of the occurrence of each special skill event (specialskill A event and special skill B event) or a date and time when it isdetermined that each criterion operation data string has been inputtedby the determining unit 52, and may acquire, as “the statistics relatedto the results of the determinations made in the past by the determiningunit 52”, the occurrence count of each special skill event during apredetermined period (e.g., period from a predetermined time ago up tothe present time) or the determination count for which the determiningunit 52 has determined that each criterion operation data string hasbeen inputted. Furthermore, for example, the statistic acquisition unit56 may acquire the occurrence count of each special skill event or thedetermination count for which the determining unit 52 had determinedthat each criterion operation data string has been inputted, in theplays (matches or battles) of the latest predetermined number of times.

Moreover, for instance, the degree of difficulty of the occurrence of acertain special skill event may further be changed based on theoccurrence count of another special skill event or the determinationcount for which the determining unit 52 has determined that a criterionoperation data string corresponding to the another special skill eventhas been inputted. For instance, the degree of difficulty of theoccurrence of the special skill A event may be changed based on a totalof the occurrence count of the special skill A event and the occurrencecount of the special skill B event.

Yet further, for example, the game to which the present invention isapplied is not limited to the game described above. The presentinvention can be applied to games other than the fighting game and alsoto games in which three or more players participate.

Further, for example, in the description above, a description has beengiven of an example where the present invention is applied to the gamesystem including one game device 10. However, the present invention canbe applied to a game system including a plurality of game device 10.

Still further, in the description above, the program is supplied to thehome game machine 11 from the DVD-ROM 25 serving as an informationstorage medium. However, the program may be distributed to homes and thelike via the communication network. FIG. 14 is a diagram illustrating anentire structure of a program distribution system using thecommunication network. A program distribution method according to thepresent invention will be described with reference to FIG. 14. Asillustrated in the figure, a program distribution system 100 includes agame database 102, a server 104, a communication network 106, a personalcomputer 108, a home game machine 110, and a PDA (personal digitalassistance) 112. A program distribution device 114 includes the gamedatabase 102 and the server 104. The communication network 106 includes,for example, the Internet or a cable TV network. In this system, thegame database (information storage medium) 102 stores a programidentical to the content stored in the DVD-ROM 25. In addition, aprospective consumer makes a game distribution request by use of thepersonal computer 108, the home game machine 110, the PDA 112, or thelike, whereby the request is transferred to the server 104 via thecommunication network 106. Then, the server 104 reads the programs fromthe game database 102 in response to the game distribution request, andtransmits the programs to the game distribution requester such as thepersonal computer 108, the home game machine 110, the PDA 112, etc.Herein, the game is distributed in response to the game distributionrequest. However, the server 104 may transmit the game in a one-sidedmanner. Further, all components of the program necessary to realize agame are not necessarily sent at once (collective distribution), andonly a necessary component of the program according to an aspect of thegame may be sent (dividing distribution). By distributing the game viathe communication network 106 as described above, the prospectiveconsumer can easily obtain the programs.

1. A game system including one or more controllers, comprising:determining means for determining whether or not a criterion operationdata string has been inputted from the one or more controllers; and gameevent generation means for generating a predetermined game eventaccording to a result of the determination made by the determiningmeans, wherein the determining means executes a change of the criterionoperation data string on the basis of a result of a past determinationon at least one of the one or more controllers.
 2. A game systemaccording to claim 1, wherein the determining means executes, whendetermining whether or not the criterion operation data string has beeninputted from one of the one or more controllers, the change on thebasis of a result of a past determination on the controller.
 3. A gamesystem according to claim 1, wherein the determining means executes,when determining whether or not the criterion operation data string hasbeen inputted from one of the one or more controllers, the change on thebasis of a result of a past determination on another controller amongthe one or more controllers.
 4. A game system according to claim 1,wherein the determining means executes the change on the basis of thenumber of times the game event generation means has generated thepredetermined game event according to the result of the determination onat least one of the one or more controllers.
 5. A control method for agame system including one or more controllers, comprising: a determiningstep of determining whether or not a criterion operation data string hasbeen inputted from the one or more controllers; and a game eventgeneration step of generating a predetermined game event according to aresult of the determination made in the determining step, wherein thedetermining step includes the step of executing a change of thecriterion operation data string on the basis of a result of a pastdetermination on at least one of the one or more controllers.
 6. Acomputer readable information storage medium storing with a program forcausing a computer to function as a game system including one or morecontrollers, and also to function as: determining means for determiningwhether or not a criterion operation data string has been inputted fromthe one or more controllers; and game event generation means forgenerating a predetermined game event according to a result of thedetermination made by the determining means, wherein the determiningmeans executes a change of the criterion operation data string on thebasis of a result of a past determination on at least one of the one ormore controllers.
 7. A game system according to claim 2, wherein thedetermining means executes the change on the basis of the number oftimes the game event generation means has generated the predeterminedgame event according to the result of the determination on at least oneof the one or more controllers.
 8. A game system according to claim 3,wherein the determining means executes the change on the basis of thenumber of times the game event generation means has generated thepredetermined game event according to the result of the determination onat least one of the one or more controllers.